As World War II loomed on the horizon and tensions reached a new high, a select few watchmakers in Florence had no time to panic. They were channelling all their focus on one of the most crucial military tools for the First Submarine Group Command of the Royal Italian Navy. Its frogman commandos — the amphibious demolition specialists — were scheduled for deployment to Africa much earlier than expected, in turn accelerating the timetables for delivery of the first specialised waterproof watch. These watchmakers were from Officine Panerai, and the timepiece in question, the Radiomir. 

More than 80 years later, the definitive Panerai military tool watch has become an icon in its own right — especially with its distinctive large cushion-shaped case and boldly numbered luminous dial — but back then it was strictly function over form. 

Tactical ambitions

It wasn’t till the eve of the Second World War that Panerai pushed through with the first prototypes of the Radiomir for the frogmen, but the watch was a long time in the making. 

The first Radiomir Prototype by Panerai.

Established in 1860 by Giovanni Panerai in the old city of Florence, the company was an office that integrated a watchmaking school, repair workshop, and sales showroom under one roof. Together with his son, Leon Francesco, Giovanni would go on to work with some of the most recognised players in the Swiss horology world in 1907, establishing supplier ties that saw movements, cases, specialised parts, tools for precision mechanisms, and even whole watches being sent to the offices whenever needed. Their exceptional reputation in the industry earned them representative rights to the likes of Rolex, Vacheron Constantin, and Patek Philippe. 

By the 20th Century, Panerai’s professional tool and hardware fabrication services were extended to the Regia Marina (the Royal Italian Navy). Giovanni’s grandson, Guido, ran the show by first providing submersible navigation tools and contact triggers for mines while working on developing a self-sustaining source of illumination for the military equipment. Radium was the shining answer to their problem, and Panerai’s resulting proprietary compound of radium bromide, zinc sulphide, and mesothorium would go on to be trademarked as ‘Radiomir’.

The Royal Italian navy wearing Panerai’s Radiomir on their missions.

The era of countless inventions and discoveries also saw Rolex — one of Panerai’s Swiss manufacturing partners — simultaneously develop a waterproof watch successfully. Named the ‘Oyster case’, the 1926 invention was a defining moment in watchmaking history when it opened the doors to practical water-resistant watches for the average consumer. With both technologies well within grasp, Panerai had the means to successfully create a waterproof timer that could assist maritime combatants with the “Davis Rebreather”, a portable underwater breathing device. 

Pioneering achievements

Panerai’s Radiomir boasted a bright lume that enabled unparalleled legibility even at low depths.

Fully assembled Ref. 2533 Oyster-cased Rolex pocket watches were ordered and the Italian firm got to work — modifying the cases, dials, and hand-wound mechanical movements for the Ref. 3646, Panerai’s first no-nonsense military tool watch. Soldered on wire lugs, highly-luminous dials, Plexiglass, aluminium sandwich dials, and waxed leather straps that were long enough to be worn over a diving suit were definitive pioneering features that became the Radiomir’s signature.

It didn’t take long for the success of the Radiomir to make waves slightly south across the map, where German military divers adopted exactly the same timepieces after attacking Italy. Dubbed the “Kampfschwimmer”, these Radiomirs were identical with their “anonymous” dials that did not have any branding whatsoever, a clever move by Panerai that absolved them from any association with the Nazis. Panerai watches remain, to this day, inextricably linked to the seminal moment in military history when the modern era of elite tactical warfare was born. 

A health ad touting the benefits of radium.

Many of the Radiomir’s features were pioneering achievements of Panerai’s and were integral to the success of the missions. However, on hindsight, they weren’t all exactly the best options, especially when the hazardous radioactivity of radium which was used to produce the watch’s signature lume was not understood until much later. Till then, the element was considered healthy and used as drugs for various ailments. Factory women who hand-painted the dials were known to lick their brushes and paint their nails with the glowing substance, only to develop radiation poisoning later on. To this day, the Radiomirs painted with radium still emit radiation despite losing their glow — though that hasn’t stopped Panerai diehards from hankering after these rare holy grail timepieces. 

While the watches too today are decked in crystal glass, Panerai Radiomirs were among the first few watches to employ Plexiglass, a revolutionary material in the 1930s. Though shunned by luxury watchmakers today, the fact that it was much harder to break than conventional glass outweighed the fact that it was easily scratched.  

Modern beginnings

Now an icon in its own right, the Panerai Radiomir has come a long, long way from its deep-seated involvement in the war. In 1949, the compound was replaced by a safer self-luminous substance called Luminor. Like its counterpart, the tritium-based compound inspired a whole new series at the watchmaking firm. 

The Panerai Radiomir 1940 Art Deco dial PAM00790.

Retrospective models like the Radiomir 1940 have spawned countless variations, with the latest being the Radiomir 1940 Art Deco Dial PAM00790 and PAM00791. A stark departure from the brand’s standard fare, the new version sees no trace of its hallmark luminescence and large numbered markings. In their places sit elegant Art Deco-styled hour numerals, a railway minute track, and — for the first time ever — spear-shaped hour and minute hands. 

Inspired not by the Italian Navy frogmen, but by Giovanni Panerai’s extensive know-how in pocket watches and pendulum clocks, the dial of the new Radiomir plays the retro card to perfection with its beige, black and ivory colourway. The domed Plexiglass crystal, though, is the cherry atop this wonderfully nostalgic sundae.

www.panerai.com

(Images: Panerai)

Shatricia Nair
Senior Writer
Shatricia Nair is a motoring, watches, and wellness writer who is perpetually knee-deep in the world of V8s, tourbillons, and the latest fitness trends. She is fuelled by peanut butter and three cups of coffee a day.